For me there is a significant issue on the "accurate colour" front. My subjects often have colour casts from light reflected from and transmitted through their surroundings (leaves, petals etc). Would using the ColorChecker adjust the colours so the subjects would appear as they would in "neutral" light? The thing is, I don't think I want to "correct" these "environmental" colour casts, because the colour, with the cast, is what it really looked like, and for me is part of the interest of the scene. Or perhaps I'm misunderstanding how these colour corrections work.

All gloriously off-topic of course. Except ... would ColorChecker adjustments work equally as well with JPEGs and RAW I wonder? I suspect they would; I think Grey card white balance adjustments work just as well with JPEG as RAW, don't they?

My understanding is that using the ColorChecker and related software allows you to create presets that tell Lightroom how to interpret the color values in the file. They don't have any effect on white balance per se. Instead, they define what "red" and "green" and "blue" should look like. For instance, if the preset created by Adobe defines "red" as "slightly orange red" most of the time, either because Adobe didn't get it right or because your particular camera and lens combination has a slightly yellow cast to it that affects all white balances (except, perhaps, Auto, which could probably compensate for the yellow color cast), then creating a preset for that camera and lens combination with the ColorChecker should more accurately represent "red," regardless of the white balance. White balance and what the ColorChecker is creating are two separate things, I think, though both affect color.

I think what I've created is a "poor man's ColorChecker." In the presets I've created, I've altered the RGB, contrast, and clarity values. When I import my images, all of them are altered in the same way, regardless of white balance, because after much trial and error, I found these particular values gave the most accurate color for my particular camera.

As to your other question, I think, from what I understand the article to be saying, that you could use it like a super gray card by shooting the ColorChecker in the ambient light you were shooting in and then later using that shot to create a preset. Apparently, if you were to shoot the ColorChecker in sunlight, shade, and shadow, you could combine a couple of these into a single preset that overall gave you more accurate color for that locale, regardless of the variation in type of light. Or you could use a different preset for the shots in sunlight, another for the ones in shade, and so on. These should still give more accurate color even when the scene itself had an overall yellow or green or red tint, due, say, to foliage or sunset.

But again, I'm just interpreting what I'm reading. I haven't tried this tool yet.